<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>
<body>
    
</body>
</html>
<script>
    var str=prompt('请输入字符串')
var o={};
for(var i=0;i<str.length;i++){
    var chars=str.charAt(i);
    if(o[chars]){
        o[chars]++;
    }else{
        o[chars]=1;
    }
}
var max=0;
var ch='';
for(var k in o){
    if(o[k]>max){
        max=o[k];
        ch=k;
    }
}
alert('出现次数最多的字符是:'+ch+'，共出现了'+max+'次')
</script>